Logically...I think she will be alright to back to HK and come back to Canada.  But  how can you so sure that her Canada visa can let her get in US?  If I am MT, i will do it if I have 100% sure.  If they don't let you get in, they can have 1000 reasons.  But I have only one reason which is 100% sure, then I don't have to worry anything.

  So how come you guys discuss about the "tax" question?

that's rite     there are a lot of grey area

ben, i see! so you were talking about entering US.  That makes sense.  I was also thinking if the stamp on the passport is good enough.  

haha      2 - 3 lugguages are good      

yea      and my work permit will expire in july     more than 3 months till expired     should work ka    and the stamp on my passport is very important for me too

she is not going to bring in alot of things, but a few very expensive items!    j/k

then when i go back HK i will apply my US VISA there  then i can go USA in summer     

Honestly....I don't worry about that does MT can get in to US with her Canadian Visa or not.  I just worry about if she can't get in to US, they will enter some information to their computer.  You know...these data will share with Canada immgr or custom too.  Just worry this information will slow down or stop the process to get her Canada citizenship.

maybe     u never know